Waterproofing plastic compositions



Patented Dec. 28, 1948 UNITED" STATES PATENT OFFICE 2,457,518 'WATEBPROOFING PLASTIC COMPOSITIONS Jafiiies Alfred Bell, Leatherhead, England, 1 assignor. to Shell Development Company, a San Francisco, Calif a corporationof Delaware N o Drawing-.1 Application May 26, 1945, Serial No. 596,101.. In Great Britain July ,11, 1944 1" .This invention relates to compositions. p It is an object of the present invention to prepare a water proof plasticcomposition which is suitable for sealing articlesagainst the intrusion 2 of water, is mechanically and chemicallyl stable up to at least 220 F. and is also a non-conductor of electricity under the electrical conditions normally obtaining in automotive and radio electrical equipment even at temperatures up to 220 F. whilst being easily mouldable in the hand and readily adhesive to wood, plastics, fabrics and metal even if these be contaminated with oil or grease.

With these objects in view the present invention provides a water proof plastic composition which consists essentially of to 35% by weight of dehydrated asbestos or other dehydrated fibre which is resistant to a temperature of at least 220 F., 25 to 55% by weight of a petroleum oil having a viscosity between 100 seconds Redwood I at 100 F. and 180 seconds Redwood I at 210 F. and 10 to 40 by weight of a water-insoluble soap.

Preferably the petroleum oil has a viscosity, Redwood I at 100 F. of between 200 and 500 seconds.

The proportions of the ingredients are such that the composition is easily mouldable in the hand and readily adhesive to wood, plastics, fabrics or metals, even if these be contaminated with oil or grease; the composition is mechanically and chemically stable at temperatures up to 220 F. in that when moulded around articles and subjected to such a temperature it does not come away, sag, bleed or otherwise disintegrate or lose its water proofing properties.

The expression dehydrated asbestos or other dehydrated fibre as used herein refers to a fibre which has a water content not exceeding 0.1% by weight when tested by Method I. P. 74/44. It will be understood, however, that the composition may contain a small proportion of water (of the order of 1%) provided that this is dispersed through the oily component and is not in the fibre.

Fibres other than asbestos which may be used are rock wool and cotton linters. Dehydration is accomplished by heating the fibre to a temperature at least 10 F. and preferably between 80 F. and 110 F. above the boiling point of water, at atmospheric pressure or under vacuum.

The plastic water proof compositions of the present invention not only have the properties referred to above but owing to the dehydration of the asbestos or other fibre are non-conductive to electricity under the conditions of voltage and s cret s. (01; 106 243) water proof plastic 1 current normally obtaining in automotive and radio electrical equipment and retain such properties at the elevated temperatures mentioned and/or when immersed in water.

The water proofing nature of the compositions of the present invention is such that they can be used for sealing articles against the intrusion of water (e. g. entry of seawater into automotive engines, gear boxes, electric equipment or the like when immersed in the sea, and entry of rain through roofs).

Preferably the asbestos or other fibre is used in a proportion of between 20 and 25% by weight of the composition.

Preferably the oil is used in a proportion of between 35 and 45% by weight of the composition.

Preferably the water-insoluble soap is used in a proportion of between 20 and 35% by Weight of the composition.

It will be understood that the relative proportions will be so chosen as to fulfil the above criteria.

The soaps may be made from bases of polyvalent metals or of lithium and fatty acids having 12 to 20 carbon atoms in the molecule, or glycerides thereof, or mixtures of the two. It is desirable, though not essential, that some Wool grease stearine be present. Preferred bases are those of the alkaline earth metals, specifically magnesium, calcium and barium, although bases of other polyvalent metals may be used, notably aluminium, zinc and cadium. Preferably the soaps are substantially free from glycerine.

The compositions of the present invention may be made in any of the conventionally known ways of manufacture of oil-soap mixtures except that it is essential to dehydrate the fibre.

Thus, for example, the composition is preferably made by mixing the fatty acids used for making the soap, and a part of the oil with the asbestos, heating the mixture, dehydrating the asbestos, cooling, adding the theoretical proportion of the base (for example calcium hydroxide) necessary to form the water-insoluble soap in the remainder of the oil and stirring the mixture.

Alternatively, the water-insoluble soap may be mixed with the oil and the previously dehydrated asbestos or other fibre incorporated with the material.

The following example, in which the parts are by Weight, illustrates how a composition of the present invention may be prepared:

26 Parts of a petroleum oil of viscosity Redwood I at 140 F. of seconds was mixed with 13.5 parts of wool grease stearine and 21 parts of 3 distilled fatty acids (consisting essentially of saturated and unsaturated fatty acids containing 16 to 18 carbon atoms in the molecule) and 22.5 parts of asbestos was stirred in with heating of the mixture to 135 C. to remove the water present in the asbestos. The mixture was cooled and 4.3 parts ;of calcium :hydroxideasuspencled 11121227 parts of the aforesaid petroleum oil was added with stirring.

I claim:

1. A waterproof plastic insulating -composition consisting essentially of -35% by weight of a dehydrated asbestos fiber havingaimoistn-rercontent not exceeding 0.1% by weightistable atltein peratures up to at least 220 F.,'25-55% by weight of a mineral lubricating oil::and1 10-'40% by weight asbestos-having. a moisture content not exceeding 0.1% by weight, about'38.7 mineralilubricating oil, and 20 to 35 of aQcalcium soap of a mixture of distilled fatty acids "having :16 to '18 carbon *Number' atoms and wool grease stearine.

. 4 3. A waterproof plastic insulating composition consisting essentially of 20 to by weight dehydrated asbestos having a moisture content not exceeding 0.1% by weight, to by weight mineral lubricating oil and 20 to 35% of a lithium soapof .a mixture of distilled fatty acids havin "16 to :18 carbon iatomsmnd W001 grease stearlne.

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iSTATES PATENTS Number I Name Date 1 ;7fi4g837 f l fodson June 17, 1930 2005356 Toohey et al July 18, 1935 2029, Hodson Jan. 21, 1936 2,068,019 Gottwald Jan. 19, 1937 .,2 ,2.52,16.9 ,Cullison Aug. 12, 1941 2,297,183 'F'abl'an-et'al -'Sept. 22, 1942 2,303,068 ,schoenibaum 11---- ;Nov.' "24, 1942 ZFQEEIGN SHAWN i153 "Goun'txy Date "136,989 fianada o l '-Nov. 28, 191 1 

